"Many people" vs. "much people" — which one should be used?

If you can count it and it doesn't designate a category, use many.

If you cannot count it or it designates a category, use much.

I have many friends.
I have much to offer.
There are many ways to get it wrong.
It doesn't make much sense.

Many is used in enumerated quantities. If it can be counted in individual items, use many. If the quantity cannot be counted, use much.

"There are so many people in here!"

"There is so much I still need to learn!"

Simple rule of thumb: if the following word is plural use many, otherwise much

"I don't have much time"

"I don't have many books"

"how much money do you have?"

"how many cars can you see?"